GoToMeeting is a good one. So is LogMeIn and TeamViewer. There are a lot of flavors you can use for remote support. If you have or are thinking about implementing Office Communicator, you can go that route too. The desktop sharing tool is just like gotomeeting.

Join.me from LogMeIn is the free, multi-user screen sharing software from LMI and it works great. Totally free, just go to the page and get a screen sharing number and post it on the board or email it out. Simple, easy, effective.